/Engine/Source/Runtime/Engine/Public/BatchedElements.h
Adds a line to the batch. Note only SE_BLEND_Opaque will be used for batched line rendering.
void AddLine ( const FVector & Start, const FVector & End, const [FLinearColor](API\Runtime\Core\Math\FLinearColor) & Color, [FHitProxyId](API\Runtime\Engine\FHitProxyId) HitProxyId, float Thickness, float DepthBias, bool bScreenSpace )